It's just a million to compute the microsecond part of the timeout...

```php
$options['timeout']  = 2.15;
$timeout_sec = (int) floor( $options['timeout'] );
$timeout_msec = $timeout_sec == $options['timeout'] ? 0 : 1000000 * $options['timeout'] % 1000000;
var_dump( $timeout_sec, $timeout_msec ); // "int 2" and "int 150000"
```

Not sure there's a point in using a class const, I think a comment would be better then :) I'm always reluctant to add comments in Request, as there is very few of them in here